Over the past few years ZMF Headphones owner Zach Mehrbach has built a strong reputation within the personal audio community as one of the foremost modders of the popular Fostex T50RP headphone.
ZMF's custom builds not only elevate the sound of the classic Fostex driver, but turn the once-humble headphones into beautiful heirloom pieces by giving future owners their choice of wood cups, sliders, pads and headbands – yielding a headphone that is totally unique. But while
ZMF's popularity grew, Mehrbach still wanted more – a headphone that was completely his own. Inspiration struck after a chance encounter with the legendary Sony R10 at an audio show. Widely considered to be one of the greatest headphones of all-time, he became enamored with the ultra-rare
R10's stunning sound quality and oddly contoured wooden cup design. The Sony's cups were machined from 200-year-old Aizu Zelkova wood into a compound curve shape. The unique structure was said to give the cup a three-dimensional form that could more realistically mimic the feel of a live concert hall.

Drawing upon this acoustic principle, Mehrbach set out to put his own totally fresh spin on the compound curve – using his woodworking expertise to experiment with different cup geometries until he found his own completely unique sound. He also added a series of five open slots around the circumference of the cups to assist in tuning the headphones, making these the first cups ever to combine the benefits of compound curve acoustics and a semi-open design. The result is two new fully-original flagship headphones, the ZMF Eikon (starting at $1299) and Atticus (starting at $999). Both headphones use an identical cup design, but the dynamic drivers found within are quite different, in both material and sound. Like the Sony R10, the Eikon uses a biocellulose diaphragm – an organic material that yields a driver with extremely low distortion levels and excellent attack and decay properties.

The other headphone, the Atticus, uses a diaphragm made from thermoplastic elastomer (TPE). This synthetic compound offers an excellent balance of elasticity and rigidity, giving it nearly ideal sonic properties. Not to be outdone, TPE also plays a key role in the diaphragm of another legendary headphone, the Sennheiser HD800. Both models are available in cherry wood or can be upgraded to padauk for an additional $100. They each clock-in with an impedance of around 300 ohms, and as is often the case with high-impedance headphones, they tend to excel when paired with OTL (output transformer-less) tube amps. Both headphones are also quite sensitive at 100dB/mW, so they were easily driven by my Acoustic Research M2 DAP ($1199). They were even able to eek out a respectable amount of volume from an iPhone 6.

They are comfortable to wear, stunning to look at... oh, and they also share one more essential trait: they both sound absolutely amazing.

Your Own Personal Concert Hall: The ZMF EikonI evaluated the ZMF Eikon in padauk and the Atticus in cherry. Of the four possible combinations of woods and drivers, these two headphones will be the farthest apart. The Eikon driver and padauk housing each being slightly more crisp and analytical sounding, while the Atticus driver and cherry cup both lean a little more to the lush and euphonic side. According to ZMF, the drivers have a larger overall impact on the final sound than the wood choice. Choosing the right one is a matter of figuring out what you value most from your headphone. The Eikon feels a little bit higher definition, offering a linear signature and exceptional clarity. There is a certain edge to the sound, which is finely contoured on the front and back end of each note. The sound is pretty linear, but a little colored overall with a bit of extra energy in the sub-bass and upper midrange. This additional emphasis makes the headphone an exceptional performer at low volumes, as the clarity and impact still shine through quite easily.

Getting into the individual frequency ranges, the bass on the Eikon is nicely extended, with a powerful sub-bass presence. Still, the decay is quick and accurate, making this headphone just as good for EDM as it is for classical. Mid-bass is briskly paced with a squeaky clean transition into the lower midrange. Adding a tube amp can offer a touch of euphonic bloom in this area, and with so much clarity to spare, I
didn't find it to hurt the Eikon's sound one bit. I found the lower midrange to be tastefully done without any additional sense of bloat. If I had to make one complaint,
It'd say the upper mids have a pinch of shouty-ness at louder volumes with some genres, but that little touch of extra presence also brought out a nice bit of an edge on guitars that made them more energetic and engaging, so
it's a bit of a tradeoff.

Treble is flat and controlled without being dull or harsh. Mehrbach credits the biocellulose driver for giving him the ability to walk this fine line with the treble so effectively. The upper treble air is quite good for a headphone that is semi-closed, giving the Eikon a more open sound than I expected. The attack and decay are very impressive here with a very quick initial transient response and a decay that hangs around just long enough to give the headphone a little pinch of extra body. The background is deep and black, which allows sounds to separate cleanly with strong imaging. The compound curve design of the cup offers obvious benefits to the overall soundscape, particularly when paired with binaural recordings and Dolby Headphone (or similar) surround processing.

Listening to Cheskey Records' binaural version of
Mozart's Divertemento in D, the "concert hall" effect is in full swing as you are transported to the symphony by simply closing your eyes. The feel of the room is full and quite realistic, which is an especially notable accomplishment since the headphone is mostly closed-back in design. Width and depth are well above average here. While large, the overall size of the soundscape
doesn't quite match the vastness of the Sennheiser HD800. However, I found that the Eikon was in many ways a good
"warmer" alternative for a change of pace from the venerable Sennheiser. This also made it a killer headphone for gaming, especially when used in conjunction with the Creative
X7's ($349) virtual headphone surround sound.

Heart, Meet Sleeve: The ZMF AtticusCompared to the Eikon, the Atticus is a bit more laid back. Where the Eikon is hard and revealing, the Atticus is soft and sweet. The sound here feels extremely natural and slightly darkened overall to my ears. From first listen, it is abundantly clear that the Atticus prioritizes musicality above all else. It is just one of those very rare headphones that manages to stay non-fatiguing without losing its sense of dynamic punch and impact. Atticus is very easy on the ears and because of that, it incredibly easy to just crank this one up and sink back into its thick and supple sound. The bass is similarly extended on the two headphones, but it seems like the Eikon may go just a touch deeper. And while the Eikon is a bit more focused in on the sub-bass region, the Atticus clearly has more mid-bass and comes across as the bassier headphone overall.

Paired with my Acoustic Research M2 DAP and my Wells Milo solid-state amplifier ($1699), I felt like the thunderous bass of the Atticus got a little excessive at times, dominating the song. Paired with higher impedance tube amps, however, something quite strange happened. Contradictory to all my expectations, the bass tightened up, seemingly storing up energy for a massive impact when it is summoned from the nether. And boy does it ever hit hard when called upon! Paired with the DecWare CSP3
($1279), an excellent OTL tube amplifier, the Atticus delivered one of the most exciting and blissful bass presentations I have ever heard. Whatever the music asked for it seemed to deliver in spades – whether it was quantity or quality.

For as great as the bass is on the Atticus, the midrange is where the headphone truly shines. This headphone is absolutely superb with vocal music. Listening to Lake Street
Dive's "Bad Self Portraits" from the album of the same name, singer Rachel Price's soulful vocals are clearly out front, delivering a powerful performance that is smooth, sumptuous and never harsh.

On the Eikon, the Price's vocal is comparatively further back, with the instruments being pushed farther forward. Head-to-head, one can see that the Eikon is the more resolving headphone, with crisper edges to each note. The Atticus is more concentrated in the body of the note than the edges. But while the Atticus might not be as crisp, it possesses superior body, musicality and emotion. Feelings just flow out of it like liquid, and it connects you to the music very closely. This headphone is all heart, and at the end of the day,
that's what makes it special. Treble is sweet and feathery soft. It has a touch more sparkle than the Eikon to my ears, which I think contributes to the better vocal presentation. The air is good, but
it's not quite as airy as the Eikon, so it doesn't sound quite as open.

The soundscape here doesn't feel quite as large as the Eikon and sounds
don't separate quite as easily. I'm sure this is partially due to the increased body, but Eikon certainly seems to have more width and depth overall. Imaging is still quite strong, you are just a bit closer to the music. In comparison to other closed and semi-open models, however, the soundscape of the Atticus is still quite a bit larger than average.

Moving on to other technicalities, the attack is a little less
"immediate" when it comes to transients and Atticus has a bit longer decay than Eikon. This contributes to a softer, more romantic sound overall but it
doesn't quite deliver the superior definition of Eikon. That being said, once the music starts flowing all this is becomes a distant memory because you are completely engaged in the song. Paired with an appropriate OTL tube amp this headphone grooves hard as hell and is easily one of the absolute best vocal headphones on the planet, particularly with female vocals were it enters into truly rarified air. Seal, Anne Bisson, Jill Scott, Fiona Apple, Erykah Badu, James Blake, Chris Isaac, Florence + the Machine – any music with powerful vocals will be handled with heart-wrenching, tear-jerking aplomb. Like I said, this one is all heart.

Final ThoughtsThese are two very good headphones and are actually quite complimentary of one another, depending on
one's taste in music. Eikon is especially good with classical, bluegrass, binaural recordings and anything that demands a
"live" feel. Atticus, on the other hand, is going to be a terrific choice for pop, hip-hop, R&B, rock, metal and jazz for its warm, forgiving nature, tremendous impact, and vocal prowess. Indeed,
it's quite rare to stumble across a headphone that can deliver elite performances with Diana Krall and Lady Gaga alike, but the Atticus does it, and does it well. Both headphones ought to be extremely popular with fans of electronic music: the Eikon for its phenomenal sub-bass performance, detailed sound and spacious feel, and the Atticus for its engaging signature and thunderous mid-bass punch.

I found the headphones to be a little picky with amplification, but not overly so.
It's just that some things worked better than others. Of the combinations I tried, I found the Cavalli Liquid Carbon ($799) to be my favorite match with the Eikon, and the DecWare CSP3 ($1279) to be the best match for the Atticus. The fantastic, but now discontinued tube-hybrid Cavalli Liquid Crimson ($2999) matched beautifully with both headphones, offering a velvety sound and sharp resolution that worked with everything I could throw at it.

A bit of caution needs to be said in that those who are looking for absolute neutrality may not be very satisfied with these headphones. They each have a bit of coloration to them. Yet those who are seeking a warm and spacious open back with buttery tone and solid technical performance should be quite pleased. The bottom line is that both of these headphones are extremely capable when it comes to the one trait that is the most important of all: delivering sweet, sweet
music.